One of the “Polish Bristols”, used to power the PZL.23A Karas.
British aviation pioneer George White founded The Bristol Aeroplane Company Ltd in 1910. The company produced aircraft and from 1920 expanded its interests to aero engines, for which it became widely known. One of the engine designers was the outstanding engineer Roy Fedden.
In the early 1930s, Poland purchased a licence from Bristol for their highly regarded 9-cylinder, high-power, air-cooled radial engines. They were intended to power the new types of military aircraft then being designed in the country. These engines, under the names Jupiter, Mercury and Pegasus, were built at the PZL WS-1 factory in Warsaw. Jupiter engines were installed on the PZL P.7 fighters, Mercury engines were intended for subsequent types of Polish fighters, and Pegasus engines for bomber and passenger aircraft.
The first version of this latter type produced in Poland was the Pegasus II, delivering 600 hp. Poland undertook licence production despite the fact that the engine was not fully developed and suffered from reduction gear overheating problems. It was replaced in production by the more successful Pegasus VIIIA engine. The Pegasus II was used to power PZL P.23A Karas aircraft.
| Configuration | 9-cylinder radial |
| Cooling | air |
| Compression ratio | 5.5 |
| Displacement | 28.0 l |
| Weight | 470 kg |
| Power | 590 hp |
